Dermatology

Salivary Gland Mucocele (Mucoocele)

Are You Confident of the Diagnosis?

Characteristic findings on physical examination

Classic mucoceles (Figure 1) account for 94% of lesions, are larger (most range from 5-10 mm), fluctuant, and nodular, with a deep blue hue or flesh toned color. Lesions are typically painless. Most (>80%) occur on the lower lip. Other sites include the mouth floor, ventral tongue, or buccal wall. Rarely (1-3%), the upper lip is involved. Sublingual lesions (ventral tongue or floor of mouth) are also called ranula (Latin: little frog) from its resemblance to a frog’s air sack.

Figure 1.

Mucocele (Courtesy of Howard Pride, MD)

Figure 2.

Histology of a mucocele.

Superficial mucoceles, a less common variant, are small (<5 mm), vesicular, frequently translucent, solitary or mutliple oral papules. Women greater than 30 years of age tend to be most affected with this subtype. Frequent sites of involvement include the soft palate, retromolar pad and posterior buccal mucosa.

Expected results of diagnostic studies

Diagnosis can be made on clinical grounds, especially with superficial vesicular variants. Deeper mucoceles typically need histopathologic examination to confirm or exclude other salivary gland tumors (Figure 2). Imaging studies such as ultrasound, computed tomography, and/or magnetic resonance imaging may rarely be needed. These can be used to identify form, size, and location relative to other organs.

Fine needle aspiration may be of use if excisional or incisional biopsy is contraindicated, particularly when a deep hemangioma is a clinical possibility. Large bore needle aspiration may also be confirmatory with the simple observation of mucous.

Who is at Risk for Developing this Disease?

No significant gender predilection exists. More than 75% occur in people younger than 40 years of age. Superficial mucoceles tend to occur in females more than 30 years of age.

What is the Cause of the Disease?

Etiology

Pathophysiology

Rupture of the minor salivary gland duct with subsequent escape of salivary mucous into the surrounding submucosa. Complete duct blockage was initially implicated as a cause but studies are not supportive. Reasons behind lower lip predilection are unknown. Prevailing theories include large tissue size of the lower lip leading to ease of trauma, greater kinematic demands with speech leading to increased manipulation, and increased density of glands leading to the simple likelihood of occurence.

Mucoceles are not true cysts (ie, lined by epithelium). They are histologically characterized by pooled mucin lined with compressed reactive granulation tissue (Figure 3). Mucin and granulation can also be haphazardly or diffusely distributed throughout the lesion.

Figure 3.

Histology overview of a mucocele.

Mucophages (macrophages with engulfed foamy mucin) are commonly seen. These should be distinguished from salivary duct cysts, which are true cysts (eg, dilitations of the salivary ducts lined by ductal epithelium) and have different clinicopathological features. Salivary duct cysts tend to enlarge in size after eating, particularly with salivary stimulating foods such as lemon drops, grapefruit and pickles.

Systemic Implications and Complications

There are no systemic disorders associated with mucoceles. There are rare reports of superficial mucoceles associated with lichen planus or lichenoid graft-vs-host-disease.

Treatment Options

-Observation, especially in children.

-Surgical intervention such as marsupialization, complete excision, or dissection.

-Other options with variable, or lower, success rates include aspiration, incision and drainage, cryosurgery, laser ablation, or sclerosing with OK-432 (Picibanil).

-For superficial mucoceles, intermittent use of high potency topical steroids can be used. Gamma-linolenic acid (oil of primrose) can also be employed.

Optimal Therapeutic Approach for this Disease

Observation is a feasible approach to treatment. Five months is adequate time for spontaneous resolution to occur, particularly in children, and is recommended by some authorities prior to surgery in this age group.

Surgical intervention is the most common therapy. Marsupialization, complete excision (mucocele with its associated minor salivary gland), or dissection can be performed. Trauma to the labial branch of the mental nerve is the greatest risk with excision and dissection techniques.

Marsupialization of the lesion is the first interventional approach to avoid mental nerve trauma. In this procedure, the lesion is unroofed, then packed with gauze for 7-10 days. Sutures may be placed laterally to keep the unroofed mucocele patent. Careful suture placement should taken with nearby glands to prevent iatrogenic mucocele formation. Sublingual or superficial lesions respond best with this technique. Deeper lesions tend to recur.

Micromarsupialization is a new novel technique used in children with lesions less than 1cm. Silk suture is placed through the internal part of the mucocele’s widest diameter, stitched, then left in place for 7 days with eventual resolution.

Complete excision simply requires removal of the lesion, some normal surrounding tissue and the underlying feeding gland en total. This technique can be performed with a scalpel, electrosurgery unit, or laser.

Dissection technique involves a superficial incision (does not penetrate the mucocele) at the lateral base of the lesion. Blunt dissection scissors are used to separate the overlying oral mucosal tissue from the underlying submucosal tissue to expose and localize the central mucocele. At the base, the feeding minor salivary gland is typically attached and should be removed.

With respect to variant techniques, aspiration or incision and drainage has a high recurrence rate but is a reasonable conservative interventional approach in children where lesions tend to involute with ease. Cryosurgery with a 30-second freeze and 1-minute thaw can be used. Damage to the lingual nerve and submandibular duct is still possible. Laser ablation (CO2 or Erbium:Yag) has been utilized with minimal complications and satisfactory aesthetic results.

OK-432 (Picibanil), a streptococcal-derived sclerosing agent, is a new alternative therapy that has been used with some success. Few studies highlight its use and it is experimental. Reported side effects include temporary local injection site discomfort, persistent fever and, rarely, shock (0.05%). It should be performed in a controlled setting by a practitioner with advanced life support experience, due to the low but possible risk of shock.

Superficial mucoceles are less problematic and can be treated conservatively with observation and intermittent use of high-dose topical steroids, such as Clobetasol ointment twice daily for 2 weeks then weekends only. Cessation can be adjusted with response and resumpton with disease flare. Gamma-linolenic acid (oil of primrose, a proglandin E precursor which has antiinflammatory and antiproliferative effects) can also be used.

Patient Management

Liquid or soft food diets after surgery are recommended. Occasional follow-up with more conservative approaches is recommended to ensure resolution.

Unusual Clinical Scenarios to Consider in Patient Management

Pain, unusual growth, or any suspicious character of a clinically suspected mucocele may need histologic confirmation to exclude a malignant neoplastic process.

What is the Evidence?

Eversole, LR. "Oral sialocysts". Arch Otolaryngol Head Neck Surg. vol. 113. 1987. pp. 51-56.

(Review of 120 cases of mucosal cysts in the oral cavity. Subtypes, demographics and prevalence of each discussed.)

Re Cecconi, D. "Mucoceles of the oral cavity: a large case series (1994-2008) and a literature review". Med Oral Patol Oral Cir Bucal 2010 Jul. vol. 15. 1. pp. e551-6.

(Clinicopathologic review of 158 oral mucoceles. Demographic, treatment and pathologic features were reviewed.)

Chi, AC, Lambert, PR, Richardson, MS, Neville, BW. "Oral mucoceles: a clinicopathologic review of 1,824 cases, including unusual variants". J Oral Maxillofac Surg. 2010 Aug 11.

(Review of clinicopathologic features of oral mucoceles and variants from a pool of 1824 cases, of which 1715 were confirmed histologically. Pathogenesis and rare variants were reviewed.)

Delbem, AC, Cunha, RF, Viera, RF, Ribeiro, LL. "Treatment of mucus retention phenomena in children by the micro-marsupialization technique: case reports". Pediatr Dent. vol. 22. 2000 Mar-Apr. pp. 155-8.

(Micro-marsupialization technique was performed in 14 patients with age range 5-9 years. Technique was decribed in detail. Twelve had full regression after 1 week of therapy and two had recurrences.)

Chaudhry, AP, Reynolds, DH, Lachapelle, LF, Vickers, RA. " A clinical and experimental study of mucocele (retention cyst)". J Dent Res. Nov-Dec. vol. 39. 1960. pp. 1253-62.

(The study reviews the gross, microscopic and basic clinical features of 66 mucoceles. The pathogenesis was also explored with rats where severance, pinching of the salivary duct rather than complete obstruction may play a role. Partial obstruction of the duct was potentially a cause but was not completely substantiated.)

García-F-Villalta, MJ, Pascual-Lopez, M, Elices, M, Dauden, E, Garcia-Diez, A, Fraga, J. "Superficial mucoceles and lichenoid graft versus host disease: report of three cases". Acta Derm Venereol. vol. 82(6). 2002. pp. 453-5.

(Three patients who underwent an allogeneic bone marrow transplantation for a chronic myelogenous leukaemia presented multiple superficial mucoceles and an oral lichenoid graft-versus-host disease. Association with lichen planus also discussed.)

Baurmash, HD. "Mucoceles and ranulas". J Oral Maxillofac Surg. vol. 61. 2003 Mar. pp. 369-78.

(General review of mucocele therapeutic modalities, surgical complications, and outcomes.)

Ohta, N, Fuckase, S, Suzuki, Y, Aoyagi, M. "Treatment of salivary mucocele of the lower lip by OK-432". Auris Nasus Larynx. vol. 38. 2011 Apr. pp. 240-3.

(The study evaluates the treatment of patients with salivary mucocele by intralesional injection with OK-432. Disappearance was observed in 16 of 20 patients, marked reduction in four of 20 patients. Side effects also discussed.)

Bodner, L, Tal, H. "Salivary gland cysts of the oral cavity: clinical observation and surgical management". Compendium. vol. 12. 1991 Mar. pp. 154-6.

(Treatment modalities for mucoceles are reviewed, with special attention to the cryosurgical technique for the treatment of oral ranulas.)
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